Donepezil is a drug having an acetylcholinesterase inhibitory action that is widely used as a medication for suppressing the progression of the symptoms of dementia in Alzheimer-type dementia, or so-called Alzheimer's disease. In Alzheimer's disease, for which impairment of the cholinergic system in the brain has been reported, an acetylcholinesterase inhibitor like donepezil increases the amount of acetylcholine in the brain, and stimulates the cholinergic system in the brain. Conventionally, examples of actually used donepezil formulations have included oral administrations, such as tablets, capsules, syrups, and granules, as well as injections and rectal administration.
However, for patients with advanced symptoms of dementia, it is often difficult for the patient to take an antidementia drug. As a dosage form that is suited to such a case, Patent Document 1 describes a transdermal formulation and a suppository that contain donepezil. However, Patent Document 1 is an invention that mainly relates to an ointment, cream, or suppository, which does not sustainably administer an active ingredient over a long period of time.
Further, in Patent Document 2, a plaster agent containing donepezil is described, which has a skin permeation rate of at least 1.2 μg/cm2/hr or higher. However, since the active ingredient is dispersed in an adhesive patch, the drug transdermal absorption properties, in particular, a rapid increase in the level of the drug in the blood after administration, are insufficient.